MAX3865: The MAX3865 Laser Driver with Automatic Modulation Control
Abstract: Attempting to obtain a large but controlled extinction ratio is ultimately the source of many problems with practical laser drivers. On the one hand the laser must never operate below the threshold current, because this will cause an unpredictable start-up delay and a poor waveform (due to relaxation oscillation), in addition to increased noise and degraded laser spectral properties ("chirp"). On the other hand, laser characteristics are somewhat variable from one to the next, and in any case they vary with temperature and age.